Study On Performance Optimization And Low Temperature Sintering Of ZrTiO₄ Based Microwave Dielectric Ceramics

In recent decades,with the rapid development of wireless communication,GPS,WIFI,cellular network and other technologies have gradually penetrated into people’s daily life.Microwave components are used as important components in resonators,filters,dielectric substrates,dielectric antennas,dielectric guided wave circuits and so on,and occupy an extremely important position.As one of the core basic materials,microwave dielectric ceramics have become the focus of many researchers.ZrTiO4-based microwave dielectric ceramics have become potential candidates for industrial applications because of their moderate dielectric constant,high quality factor and low price.Unfortunately,their poor temperature stability and extremely high sintering temperature（≥1600°C）weaken their commercial value seriously.In this paper,the doping optimization was carried out to solve the temperature stability,and discussed the relationship between microwave dielectric properties and XRD phase structure,SEM microstructure and Raman/infrared spectra.After that,the low temperature sintering was studied in order to solve the problem that the sintering temperature was too high,and the mechanism of sintering auxiliaries to reduce the sintering temperature was analyzed.In this paper,the effects of(Al_1/2Nb_1/2)O₂ and(Mg_1/3Sb_2/3)O ₂ doping substitution on the sintering and microwave dielectric properties of ZrTiO₄ were studied firstly.The results show that both(Al_1/2Nb_1/2)O₂ and(Mg_1/3Sb_2/3)O₂ can enter the ZrTiO₄ lattice completely within a certain solution limit with the sintering aids of 0.5wt%CuO.For(Al_1/2Nb_1/2)O₂ doping,the formula can be simplified as（ZrTi）_1-x(Al_1/2Nb_1/2)_2xO₄（0.12≤x≤0.30）.The experimental results show that the optimum performance appears at x=0.18,and its microwave dielectric properties are as follows:ε_r=36.5,Q×f=36200 GHz,τ_f=0ppm/°C.In addition,the phonon vibration mode was further studied by means of raman and infrared spectroscopy,which verified the variation trend of microwave dielectric properties.For(Mg_1/3Sb_2/3)O₂ doping,the formula can be simplified as（ZrTi）_1-x(Al_1/2Nb_1/2)_2xO₄（0.04≤x≤0.36）.The experimental results show that the optimum performance appears at x=0.16,and its microwave dielectric properties are as follows:ε_r=31.9,Q×f=41200 GHz,τ_f=+0.7ppm/°C.In addition,the phonon vibration mode was further studied by means of raman and infrared spectroscopy,which verified the variation trend of microwave dielectric properties.Based on the above experimental results,when 0.5wt%CuO is added as sintering aid,the sintering temperature decreases to a certain extent,but the sintering temperature is still high,which is not conducive to industrial production.In order to further reduce the sintering temperature,BaCu（B₂O₅）was used to reduce the sintering temperature of（ZrTi）_0.84(Mg_1/3Sb_2/3)_0.32O₄ ceramics for the first time.The results show that the sintering temperature of pure（ZrTi）_0.84(Mg_1/3Sb_2/3)_0.32O₄ is as high as 1525°C,and that of 5wt%BaCu（B₂O₅）is 1075°C,and its microwave dielectric properties are as follows:ε_r=27.5,Q×f=24900 GHz,τ_f=-12.4ppm/°C.It can be seen that BaCu（B₂O₅）can significantly reduce the sintering temperature,and the microwave dielectric ceramic can still maintain excellent microwave dielectric properties.